<template>
	<view>
		<view
			id="_drag_button"
			class="drag"
			:style="'left: ' + left + 'px; top:' + top + 'px;'"
			@touchstart="touchstart"
			@touchmove.stop.prevent="touchmove"
			@touchend="touchend"
			@click.stop.prevent="click"
			:class="{transition: isDock && !isMove }"
		>

			<text>安德森激发i是代表发生</text>
		</view>
	</view>
</template>

<script>
export default {
	name: 'drag-button',
	props: {
		isDock: {
			type: Boolean,
			default: false
		},
		existTabBar: {
			type: Boolean,
			default: false
		}
	},
	data() {
		return {
			top: 0,
			left: 0,
			width: 0,
			height: 0,
			offsetWidth: 0,
			offsetHeight: 0,
			windowWidth: 0,
			windowHeight: 0,
			isMove: true,
			edge: 10,
			text: '按钮'
		}
	},
	mounted() {
		const sys = uni.getSystemInfoSync()

		this.windowWidth = sys.windowWidth
		this.windowHeight = sys.windowHeight

		// #ifdef APP-PLUS
		this.existTabBar && (this.windowHeight -= 50)
		// #endif
		if (sys.windowTop) {
			this.windowHeight += sys.windowTop
		}
		console.log(sys)

		const query = uni.createSelectorQuery().in(this)
		query.select('#_drag_button').boundingClientRect(data => {
			this.width = data.width
			this.height = data.height
			this.offsetWidth = data.width / 2
			this.offsetHeight = data.height / 2
			this.left = this.windowWidth - this.width - this.edge
			this.top = this.windowHeight - this.height - this.edge
		}).exec()
	},
	methods: {
		click() {
			this.$emit('btnClick')
		},
		touchstart(e) {
			this.$emit('btnTouchstart')
		},
		touchmove(e) {
			// 单指触摸
			if (e.touches.length !== 1) {
				return false
			}

			this.isMove = true

			this.left = e.touches[0].clientX - this.offsetWidth

			let clientY = e.touches[0].clientY - this.offsetHeight
			// #ifdef H5
			clientY += this.height
			// #endif
			let edgeBottom = this.windowHeight - this.height - this.edge

			// 上下触及边界
			if (clientY < this.edge) {
				this.top = this.edge
			} else if (clientY > edgeBottom) {
				this.top = edgeBottom
			} else {
				this.top = clientY
			}
		},
		touchend(e) {
			if (this.isDock) {
				let edgeRigth = this.windowWidth - this.width - this.edge

				if (this.left < this.windowWidth / 2 - this.offsetWidth) {
					this.left = this.edge
				} else {
					this.left = edgeRigth
				}
			}

			this.isMove = false

			this.$emit('btnTouchend')
		}
	}}
</script>

<style lang="scss">
	.drag {
		display: flex;
		justify-content: center;
		align-items: center;
		background-color: rgba(0, 0, 0, 0.5);
		box-shadow: 0 0 6upx rgba(0, 0, 0, 0.4);
		color: $uni-text-color-inverse;
		width: 80upx;
		height: 80upx;
		border-radius: 50%;
		font-size: $uni-font-size-sm;
		position: fixed;
		z-index: 999999;

		&.transition {
			transition: left .3s ease,top .3s ease;
		}
	}

</style>
